The present invention generally relates to lighting apparatuses. The incandescent light bulb has been the light bulb standard in both commercial and residential lighting applications for more than one hundred years. The incandescent light bulb was invented in the early 1800's, but it did not become commonly used until the late 1800's. The incandescent light bulb creates light when an electric current is passed through a filament that is suspended in a vacuum. The resistivity of the filament causes the filament to heat up and glow as the electric current passes through it. Incandescent light bulbs are relatively inexpensive and easy to manufacture in a variety of shapes and sizes. Despite this, incandescent light bulbs are falling out of favor because of the energy required to power them. There are laws in place in the United States that will cause the use of incandescent light bulbs to be slowly phased out in coming years. Additionally, incandescent light bulbs can become very hot if left on for long periods of time, and they burn out and have to be replaced every 1000 to 2000 hours of use.
Fluorescent light bulbs have also become very common over the last several decades. Fluorescent light bulbs are generally constructed out of long glass tubes. The tube is filled with a gas containing mercury vapor and argon, xenon, neon, or krypton under pressure. The inner surface of the tube is coated with a fluorescent material. The tube also contains a coiled electrode that emits electrons which in turn excite the mercury vapor. The excited mercury atoms produce short-wave ultraviolet light which causes inner coating of the tube to fluoresce, producing visible light. Fluorescent light bulbs last longer than incandescent light bulbs (typically 10 times longer) and require less energy to operate. Additionally, fluorescent light bulbs do not get as hot as incandescent light bulbs. Despite these advantages, fluorescent lights are not universally favored. Fluorescent lights take longer to turn on, and tend to flicker as the tube gets old. Also, the light produced by a fluorescent bulb is often considered to be glaring and not ideal for use by those with sensitive eyes.
The newest light source to come into use in recent years is the Light Emitting Diode, commonly called an LED. LEDs are miniature semi-conductors that produce light when electrons are allowed to recombine with electron holes within the device, releasing energy in the form of photons. Different colors of light are created by changing the type of semi-conductor, as well as changing the color of the plastic housing of the LED. LEDs are attractive as a light source because they emit more light per watt than incandescent light bulbs and their efficiency is not affected by shape or size like a fluorescent light bulb. LEDs last much longer than both incandescent and fluorescent light bulbs. LEDs light up very quickly and are ideal for frequent on-off cycling. Also, LEDs are made of solid-state components, so they are very shock resistant unlike incandescent and fluorescent light bulbs which are extremely fragile.
Despite the advantages of LEDs lights, LEDs still have some problems. First, the light produced by an LED is very bright and often too harsh for use in-doors. Additionally, LED performance is largely dependent on the ambient temperature of the environment where it is operating. If the LED is operating in a warmer environment, the device will fail due to overheating. For this reason, LED lights require adequate heat sinking in order to maintain long life. A heat sink is a separate device that transfers heat generated within the LED to a fluid medium, usually air. The most efficient heat sinks are ones that move air across a heated area in order to cool it down. But including a fan in an LED assembly is impractical because of size and power restrictions.
Accordingly, there is a need for an LED lighting apparatus that creates a softer light source that is more appropriate for indoor use. Additionally, there is a need for an LED lighting apparatus that effectively sinks the heat away from the LED light so that the lifetime of the LED can be maximized.